Stability of TiN(001) surfaces in humid air and aqueous environments using ab initio thermodynamics and implicit solvation methods

Density functional theory calculations combined with ab initio thermodynamics and implicit solvation models were employed to investigate the structural and thermodynamic stability of TiN(001) surfaces in humid air and aqueous environments. The results reveal that surface oxidation is the thermodynamically preferred state under humid air conditions, associated with strong structural reconstruction of the topmost TiN layer. In aqueous solution, instead, a variety of hydrogen-rich surface configurations become stable, highlighting the significant role of solvent-mediated effects. Moreover, implicit solvation is demonstrated to be crucial for accurately determining the phase boundaries between stable surface states in potential-pH Pourbaix diagrams, emphasizing its importance in modeling electrochemical interfaces for transition metal nitrides.